A heat exchanger includes a core having a plurality of tubes and a plurality of fins that are stacked with one another. The core is formed by brazing the fins and the tubes to each other. To enhance heat releasing performance, fins are typically formed from thin metal, and therefore the fins may be easily damaged. For example, during operation of the heat exchanger, tubes may expand due to heat expansion characteristics. Therefore, the fins receive stresses arising from the heat expansion, which may cause the fins to be damaged.